Nigeria among 19 countries at risk from sea level rise

Going by the recent report by Climate Central, an organization that is consistently monitoring climate change and its effects globally, 20 countries are said to be at risk from sea level rise.

The countries included Nigeria where one percent of the population may likely be affected, especially, in the coastal areas, while China, Vietnam, Japan, India Philippines and Netherlands, among others are the potential countries that may likely be affected.

According to the report, people living on land that will be below sea level or chronic flood levels by the end of the century, assuming current emissions trends continue, and medium sensitivity of sea level to warming are in danger of climate change effects.

However, some countries, such as the Netherlands, have levees that may provide protection.

Although, Nigeria may not have prepare like the Netherlands, but credit must be giving to Lagos State for taking proactive measures for the last four years, especially, in the area of annual sensitization programmes.

In a just concluded novel analysis of worldwide exposure to sea level rise and coastal flooding, the group found that 147 to 216 million people live on land that will be below sea level or regular flood levels by the end of the century, assuming emissions of heat-trapping gases continue on their current trend.

“By far, says the report, “the largest group — 41 to 63 million — lives in China. The ranges depend on the ultimate sensitivity of sea level to warming.

“But even these figures may be two to three times too low, meaning as many as 650 million people may be threatened”.

The analysis relied on global data on elevation and population, but our experience using similar data in the U.S. strongly suggests that this global data is not as accurate or precise as more modern data sources.

Comparing results for U.S. vulnerability using global data and state-of-the-art domestic data, we found that global elevation data led to major underestimates compared to modern U.S. elevation data (by a factor of 3 to 4), whereas global population data led to overestimates by a factor of 1.6 to 1.8. The net effect of global data was underestimation by a factor of 2 to 3.

If the overall error factors we calculated for the U.S. apply globally, then 300 to 650 million people live on land that will be submerged or exposed to chronic flooding, by 2100, under current emission trends.

Identical sections of northern New Jersey at 6 feet of flood waters illustrate the differences between the global data (left) and the more granular and precise U.S. data (right) (Climate Central)

Higher-quality global data — and in particular, elevation data — is needed to help resolve those figures — and makes a bigger difference than resolving sea level sensitivity. But our unadjusted results still give an indication of how nations compare in the threats they face from rising seas.

The top-20 list of most exposed countries includes representatives from every continent except Australia. The top seven slots, and 12 overall, come from Asia. Five European Union members make the list, as do the U.S., Brazil, and Nigeria.

The report stated that for its global analysis, it used land elevation data from the Shuttle Radar Topography Mission (SRTM); mean sea surface elevation data based on a 16-year record of satellite altimetry from the TOPEX/Poseidon mission; a global grid of mean annual maximum water level offsets developed by Merrifield et al. (2013); a global set of local sea level rise projections from Kopp et al. (2014); 2010 population data from LandScan; and national boundaries from GADM Version 2.0.

We believe this global sea level exposure analysis is the first to incorporate observed sea surface elevations, to factor in mean annual maximum water levels, to tie these to land elevations, and to use probabilistic local sea level rise projections.

The researchers also employed nearest neighbor approaches whenever spatial interpolation was required to match data layers. We counted as exposed all land below each water level assessed, regardless of connectivity to ocean at that level, so long as the land fell within a more broadly defined Low Elevation Coastal Zone within 10 vertical meters of the high tide line.

Thus we did not count inland depressions such as the Caspian Sea Depression, but did capture apparently isolated low-lying areas, which more accurate elevation data might prove connected.

SRTM data do not cover latitudes farther north than 60 degrees or farther south than 56 degrees, slightly diminishing our exposure estimates for Canada, Russia, and the world as a whole.

For our analysis of error over the U.S., we used lidar (laser-based) coastal elevation data from NOAA, and U.S. Census population data at Census block resolution. We excluded Rhode Island and Virginia from the analysis due to gaps in SRTM data.

This item originally appeared on Guuardian news